Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a color filter substrate with a color filter formed thereon.
Discussion of the Related Art
Liquid crystal display (LCD) devices are widely used in various fields such as notebook computers, monitors, spacecraft and aircraft applications, and etc. owing to such advantages as good portability and low power consumption associated with low operating voltage.
An LCD device includes a lower substrate, an upper substrate, and a liquid crystal layer formed between the lower and upper substrates. The light transmittance is controlled by the electric field applied to the liquid crystal layer to change its alignment status, to thereby display images.
Hereinafter, an LCD device according to the related art will be described in detail. FIG. 1A is a plan view showing the related art LCD device, and FIG. 1B is a cross-sectional view along line I-I′ of FIG. 1A.
As shown in FIG. 1A, the related art LCD device 1 includes an active area and a peripheral area. The active area corresponds to an area for displaying images thereon, and the peripheral area corresponds to an area surrounding the active area, on which images are not displayed.
As shown in FIG. 1B, the related art LCD device 1 includes an upper substrate 10, a lower substrate 20, and a liquid crystal layer 30. On the upper substrate 10, and more particularly, its one surface confronting the liquid crystal layer 30, are a light shielding layer 12 and a color filter layer 14. The upper substrate 10 is referred to as a color filter substrate.
The light shielding layer 12 is provided to prevent a light leakage. In the peripheral area on which images are not displayed, the light shielding layer 12 is formed on the entire region. Meanwhile, in the active area on which images are displayed, the light shielding layer 12 is formed in a matrix configuration thereon so as to prevent a light leakage in the boundaries between the pixels.
The color filter layer 14 is formed in the active area so as to display images in color. The color filter layer 14 is formed between each pattern of the light shielding layer 12 of the matrix configuration. The color filter layer 14 further includes red (R) color filters, green (G) color filters, and blue (B) color filters.
Although not shown, on the lower substrate 20, and more particularly, its one surface confronting the liquid crystal layer 30, are a thin film transistor functioning as a switching element, a pixel electrode connected with the thin film transistor, and a common electrode for forming an electric field together with the pixel electrode. The lower substrate 20 is referred to as a thin film transistor substrate.
The liquid crystal layer 30 is formed between the upper substrate 10 and the lower substrate 20. Liquid crystal molecules in the liquid crystal layer 30 are aligned by the electric field formed between the pixel electrode and the common electrode.
However, the related art LCD device may have the following disadvantages. The related art LCD device has a large reflectance difference between the active area and the peripheral area in response to external light. That is, when the external light is incident on the upper substrate 10, the incident light is reflected on the light shielding layer 12 of the peripheral area. The incident light on the active area, which passes through the color filter layer 14, is, however, reflected on the lower substrate 20. Thus, while the reflectance of incident light in the peripheral area is about 4%, the reflectance of incident light in the active area is about 1%. Thus, the user's visual perception characteristics may be deteriorated due to the large reflectance difference between the active area and the peripheral area.